Lubricant additive



Patented July 31, 1951 LUBRICANT ADDITIVE Elmer B. Cypher-s, flranford, and Jeffrey H. Bartlett, Westfleld, N. J., assignors to Standard 011 Development Company, a corporation of Delaware I No Drawing. Application June 24, 1948, Serial No. 35,054

Claims. (Cl. 252-32.?)

The present invention relates to an improvement in lubricant additives and more particularly to an additive which has the combined properties of improving the viscosity index, de-

pressing the pour point. and imparting extreme pressure characteristics to lubricating oils and the like.

For many purposes it is highly desirable to employ a lubricant which has greater load carrying properties than ordinary mineral base lubricating oils. It is also frequently desirable, in the use of mineral lubricating oils, to add to such oils a material which will keep them fluid at low temperatures and will also increase their viscosity at higher temperatures. A uniform or substantially uniform viscosity over a wide range of temperatures is very desirable where operating temperatures vary considerably and particularly where unit loads borne by mechanical elements are igh.

In the prior art it has commonly been considered necessary to add several materials to lubricating oils to accomplish the various purposes referred to above. Thus, where it has been desirable to increase the unit load carrying capacity of a lubricant various extreme pressure agents have been incorporated in lubricants. These have usually included a composition capable of releasing free or active phosphorous, sulfur, or chlorine, which, when the ordinary lubricating fllm fails, will immediately react with the metal to form a protective metal sulfide, phosphide, chloride, or the like, on the surface of the metal.

Where it has been found desirable to lower the pour point of a mineral oil lubricant, this has been accomplished in the past, as a general rule, by addition to the oil of a material which tends to improve fluidity at low temperatures, such as a high molecular weight condensation product of chlorwax and naphthalene. For improving the viscosity index still another composition, such as a viscous polymer of isobutylene, rubber or rubber like material has been added.

' The present invention has for its object the production and use of a single composition which may be added to mineral base lubricants and the like to impart all of the desirable characteristics mentioned above. Thus the material with which this invention deals has extreme pressure properties, tends to lower the pour point, and improves the viscosity index of mineral oils because it incorporates all, the various chemical elements and properties which produce these separate results.

The preferred material for accomplishing the results outlined above is a high molecular weight condensation product which is prepared by combining halogenated esters or halogenated polyesters with a suitable metal salt of an alkylated phosphorus-sulfur compound. Such a material 2 may be prepared, for example, by reacting a metal salt of a dialkylated thiophosphoric acid. or of a dialkylated thiophosphorous, acid, or a mixture thereof, with halogenated esters, halogenated polyesters, or halogenated copolymers of two or more esters, or halogenated copolymers of one or more esters with other unsaturated compounds, such as styrene, isobutylene and the like.

The types of esters and polymers etc., which may be employed for condensation with the metal salts are set forth more fully hereinafter. The invention will be more fully described byreferences to certain specific compositions and methods of preparation.

EXAMPLEI A halogenated ester material charging into athree liter the following materials:

348 g. mono-chlormaleic anhydride 1037.5 g. commercial mixture of C10 to Cu aliphatic alcohols, known as Lorol B, predominating in lauryl alcohol 1.5 g. sulfosalicylic acid 300 cc. 54 naphtha was produced by three necked flask The flask was equipped with a thermometer, a

Sapomflcation number=333.7 Neutralization number=3.19 Percent chlorine=654 Saybolt viscosity at 210 F.=48.5

The ester produced above, which may be referred to as an alkyl chlormaleate wherein the alkyl radical was a mixture of C10 to C18 straight chain radicals, was next copolymerized with vinyl acetate.

A one liter four necked flask, equipped with a thermometer, a stirrer, and a condenser, was next charged with 540 gramsof the alkyl chlormaleate produced by the process described above. After the ester was heated to C. the air was displaced with nitrogen and 6.0 grams of benzoyl peroxide were added. The mixture. was then blown again with nitrogen to remove any traces of air and 60 grams of vinyl acetate were added through the condenser. The mixture was then allowed to polymerize for 16 hours at 70 C. The resulting copolymer was of a very viscous con- 3 sistencyandonanalyslswasfoundtohavea chlorine content of 5.04% U weight.

The copolymer produced as described above was next condensed with a thiophosphate of sodium as will next be described.

To 830 grams of the commercial mixture of aliphatic alcohols mentioned above and commonly known as "Lorol B." there were added 222 grams of phosphorus pentasulflde (P185) with stirring at room temperature. After thorough mixing, the temperature wasraised slowly to 210 1''. and was held at that point for 3% hours. Thereafter the product was cooled and flltered. During this operation a reaction occurred which appears to be substanthlly as follows:

no s 430K ms. s me no an where R is the mixed aliphatic-alcohol radical.

V The sodium salt of the above described dialkyl dlthlophosphoric acid was prepared by neutralization with sodium hydroxirb. 7.7 grams of sodium hydroxide were disulved in 320 cc. of warm absolute ethyl alcohol and this mixture was poured slowly into 106 grams of thiophosphoric acid compound obtained in the foregoing reaction. The mixture was stirred constantly during the addition of the sodium hydroxide. The

resulting solution containedthe sodium salt of solution of the metal salt. :50 grams oi the co- 4 polymer of alkylated chlorrlmleate and vinyl acetate were heated to a tanperature oi approximately 150 F. To this was added the entire amount of the ethyl alcohol solution of the sodium salt of thiophosphoric acid ducribed above. The salt of a thioplmsphomus acid could be added in a similar manner if desired. The solution was added gradually over a period of "15 to 20 minutes. Thereafter the mixture was heated to refluxing temperature (178' P.) and was refluxed continuously for a period of hours. At the end of the refluxing period the mixture was allowed to cool and settle and it separated into two layers.

The two layers were separated by drawing off the upper layer which contained most of the alcohol. Thereafter both layers were treated to remove the volatile solvent by evaporation with the aid of added bensol and nitrogen. The materials obtained from the respective layers and their sulfur, phospbonis. and chlorine contents respectively are indicated in the following data:

Extract to (top bottom m) w) or n Phosphorus, Per Ceu 3.98 0. 82 Chlorine, Per Cant..--.. 0. as 4.47

EXAMPLE II A second sample of a copolymer of Lorol B V chlormaleate and vinyl acetate was prepared as described in Example I, and reacted with sodium di(Lorol B) dithiophosphate as follows: 102 grams of di(l.iorol B) dithiophosphoric acid and 242 grams of absolute ethyl alcohol (solvent) were stirred in a 3-necked flask equipped with a reflux condenser. 12.4 grams of sodium methoxide were added in small increments, and after this addition was completed the mixture was heated to reflux and then cooled to 120 F. 242 grams or the Lorol B chlormaleate-vinyl acetate copolymer previously described were then added and the mixture stirred and heated to reflux, continuing refluxing for three hours. The product was then cooled and flltered and the solvent removed by vacuum stripping.

The product was found to contain the following active elements:

Per cent Phosphorus 1.77 Sulfur 1.98 Chloririe 3,94

The respective materials taken from the extract and raillnate respectively of Example I and the whole product of Example II were added in small quantities to mineral lubricating oils to determine their ciiectiveness in improving viscosity index, depressing the pour point, and imparting extreme pressure properties. The results are shown in the following table:

Table POUR DEPBISSANT PROPERTIES Pour Point, F.

Mineral Oil Additive Example Example I II A None A A 0, Fxh'art A 0. ,Whole Product 5 B Nnna B 0 2% Raiflnate B 0. 0 Extract B 0.2% Whole Product 0 nm 0 0.2% Whole Product mum: on Additive Non 10% Rafllnate (Example 1)....

EXTREME PRESSURE PROPERTIES -0 Mineral on D +10% Whole Product (Example II) +10% Ramnate (Example 1 70 DESCRIPTION OF MINERAL OIL STOCKS A. Mid-Continent neutral containing 3% bright stock, the whole beln of S. A. E. 10 ade.

B. lid-Con nent extract 8. A. E. 10 blend,

C. Pennsylvania neutral oil of 180 BUS at 100' F.

D. steam reflned Penns lvania cylinder stock. p Mid-Continentacid reilned lu ricatlng stock of SUS is via/210.

From the foregoing data it appears that the condensation product, particularly the raifinate, but also the extract, or the unextracted product combines in very good measure the properties of a pour depressant, a viscosity index improving agent, and an extreme pressure agent in a single additive. The material is considered superior to compositions previously known and it appears to have unusual merit. The alkyl radicals ofthe dialkylated thiophosphorus compound may vary considerably from 6 to 22 carbon atoms for example, 8 to 18 being preferred. Single aliphatic alcohols may be used for alkylating the phosphorus-sulfur composition, such as lauryl alcohol, and any of the aliphatic alcohols having 6 to 18 carbon atoms may be used singly or in combination. An average chain length in the alcohol groups in the C10 to C14 range is especially preferred when pour point depression is the primary objective.

The halogenated esters from which the final condensation products are formed may include the following classes of compounds:

A. Polymers and copolymers of esters of halogenated a-fi. unsaturated carboxylic acids; for example, esters of chlorocrotonic acid, chloromaleic acid, dichloromaleic acid, chlorofumaric acid, chloroacrylic acid, chloromethacrylic acid, chlorocitraconic acid, chloromesaconic acid, chloroitaconic acid, and the like, as well as the corresponding bromoand iodo-derivatives.

B. Polymers and copolymers of esters of a-B unsaturated acids and halogenated alcohols, for example, esters of the chlorohydrins, bromohydrins, etc., with crotonic, maleic, fumaric, acrylic, methaccrylic citraconic, mesaconic, and itaconic acids, and the like.

C. Polymers and copolymers of vinyl and allyl esters of chloroacids, for example, vinyl chloracetate, allyl chlorostearate and similar esters.

D. Polymers and copolymers of halogenated allylor substituted allyl-esters of carboxylic acids, such 'as beta-chlorallyl esters, chlorocrotyl esters, etc.

E. Copolymers of vinyl chloride with unsaturated esters, preferably aliphatic, such as vinyl palmitate, vinyl stearate and the like.

F. High molecular weight monomeric esters derived from halogenated hydroxy compounds having 3 to 6 carbon atoms, for example, glyceryl monochlorhydrin, glyceryl dichlorhydrin, monochlor trihydroxy butane, dichlor dihydroxy butane, trichlor monohydroxy butane, 1,2-dichlor-3-alkoxy-4-hydroxy butane, halogenated derivatives of higher hydroxylated compounds such as sorbitol, mannitol, polyvinyl alcohol, etc.

G. Monomeric and polymeric esters which have been halogenated, for example, cocoanut oil, lard oil, blown rapeseed oil, fumarate polymers, acrylate polymers, etc.

The invention, as described above, thus comprises several important but related aspects. When 0.02 to 20% of the condensation product is added to an oil, the oil, either mineral base or synthetic (preferably the former for reasons of economy) may be used directly or may be marketed or otherwise used as a concentrate of the additive, to be further diluted as desired.

The proportions also depend on the purpose, as

pointed out below.

The additive itself also may be marketed for use in lubricating oils, cutting oils, extreme pressure compounds, greases, hydraulic oils and the like. The additive, in general terms, is seen to consist essentially of a condensation product of metal alkyl thiophosphorus salt (e. g.- metal alkyl thiophosphate or phosphite), with an organic, halogen-containing material, preferably aliphatic, selected from the following (1) polymers or copolymers of unsaturated monomeric esters wherein either the unsaturation or the halogen is in either the acid or the alcohol group (types A, B, C and D, listed above), (2) copolymers of vinyl halide, especially vinyl chloride, with unsaturated esters (as in type E above), (3) high molecular weight monomeric esters of halogencontaining hydroxy compounds, such as glyceryl monochlorohydrin, etc. (typeF above), and (4) halogenated esters such as cocoanut oil, fumarate ester polymers, etc. (type G above).

The invention comprises also certain process aspects, e. g., in one embodiment it involves esterifying a halogen-containing unsaturated acidic material, for example, chlormaleic acid or anhydride, with a suitable alcohol, such as allphatic alcohol, preferably saturated, having 10 to 18 carbon atoms. An elevated temperature such as 200 to 300 F. is preferably employed, it being desirable to remove water of esterification.

The acidic material or the alcohol must contain a halogen and one of them must contain an unsaturated linkage. The ester thus produced is next copolymerized with a suitable vinyl compound such as vinyl acetate. This is carried out at a temperature in the range from 70 F. to 300 F., preferably from 140 F. to 210 F. An inert solvent such as naphtha or light lubricating oil may be employed in order to control molecular weight within desired limits. Such limits are preferably about 1000 to 25,000, especially 5000 to 15,000, but may be beyond either limit. A peroxide catalyst may be employed, e. g., benzoyl peroxide, and a promoter may be employed to activate the catalyst, if desired.

The copolymer, produced as above, is finally condensed with the metal alkyl thiophosphorus salt, such as sodium dialkyl dithiophosphate. Preferably, the latter reaction is carried out between the temperature limits of about and 200 F.

The quantity of additive which should be employed in a lubricating oil will depend largely upon the use to be made thereof. As will be noted from the table, a very small amount shows an important effect upon the pour point of the ofl. For this purpose as little as .02% by weight of the product, preferably the raflinate, may be used, although normally the quantity will be from 0.1 to 1% or 2% by weight. On the other hand, for improving the viscosity index or for carrying heavy loads as an extreme pressure lubricant, the quantity employed is preferably considerably more, for example, 2 to 20% of the total lubricant. A quantity of the order of 5 to 15% is preferred; for example, 10% being recommended for normal extreme pressure use.

The base stock into which these additives are incorporated may be petroleum or synthetic hydrocarbon oils of the lubricating oil viscosity range, or lighter oils, such as those of the kerosene, gas oil, etc. range which are especially suitable for use as hydraulic fiuids. I

It will be understood that the invention contemplates the manufacture and marketing of the additive per se as a composition of matter and also contemplates its manufacture and sale as an ingredient of prepared lubricating compositions. The material may be used in greases, metal working lubricants, etc., as well as in lubricating oils and it will be understood that various con- 1 ventional additives such as oxidation inhibitors, rust inhibitors, tackiness agents. and the like, may be included as will be obvious to those skilled in the art.

What is claimed is:

l. A 'lubricating composition consisting essentially of a mineral base lubricating oil containing 0.02 to 20%. by weight, based on the total composition, of the oil soluble condensation product of a Ca to Ca: dialkylated dithiophosphate salt of alkali metal condensed at a temperature of about 100 to 200 1''. with a copolymer of Ca to Cu aliphatic chlormaleate with vinyl acetate, said copolymer being produced at a temperature within the range of about 70 to 300 F. and having a molecular weight between about 1000 and 25,000.

2. As a, new composition, the oil soluble condensation product of a sodium salt or a Co to Cu dialkyl dithiophosphate condensed at a temperature 01' about 100 to 200 F. with a 1000 to 25,000 molecular weight copolymer of Co to C22 alkyl chlormaleate and vinyl acetate.

3. As a new composition, the oil soluble condensation product 01' a sodium salt of a C10 to Cu dialkyi dithiophosphate condensed at a temperature of about 100 to 200 F. with a 1000 to 25,000 molecular weight copolymer of C10 to C1: alkyl chlormaleate and vinyl acetate.

4. A lubricating composition consisting essentially of a mineral base lubricating oil containing 0.02 to 20%, by weight, based on the total composition, 0! the oil soluble condensation product of a C10 to C1; dialkylated dithiophosphate salt 01' alkali metal condensed at a temperature of about 100 to 200 F. with a 1000 to 25,000 molecular weight copolymer of C10 to Cu alkyl chiormaleate with vinyl acetate.

5. The process which comprises esterifying monochlormaleic anhydride with aliphatic alcohol having 10 to 18 carbon atoms at a temperature of 200 to 300 F., copolymerizing said ester with vinyl acetate at a temperature of 140 F. to 210 F. in thepresence of a peroxide catalyst, and condensing said copolymer with an alkali metal dialkyl dithiophosphate having 6 to 22 carbon atoms in each alkyl group, at a temperature of 100 to 200 F.

ELMER B. CYPHERS. JEFFREY H. BARTLETT.

REFERENCES CITED v The following references are of record in the file 01 this patent:

UNITED STATES PATENTS Number Name Date 2,261,047 Assefl Oct. 28, 1941 2,266,514 Romieux Dec. 16, 1941 2,444,948 Musselman July 13, 1948 

1. A LUBRICATING COMPOSITION CONSISTING ESSENTIALLY OF A MINERAL BASE LUBRICATING OIL CONTAINING 0.02 TO 20%, BY WEIGHT, BASED ON THE TOTAL COMPOSITION, OF THE OIL SOLUBLE CONDENSATION PRODUCT OF A C6 TO C22 DIALKYLATED DITHIOPHOSPHATE SALT OF ALKALI METAL CONDENSED AT A TEMPERATURE OF ABOUT 100 TO 200* F. WITH A COPOLYMER OF C6 TO C22 ALIPHATIC CHLORMALEATE WITH VINYL ACETATE, SAID COPOLYMER BEING PRODUCED AT A TEMPERATURE WITHIN THE RANGE OF ABOUT 70* TO 300* F. AND HAVING A MOLECULAR WEIGHT BETWEEN ABOUT 1000 AND 25,000. 